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Author Topic: Oil viscosity and mpg Back to Topics
Alexi7

All-Star Author
Ohio

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Message Posted: Jan 26, 2013 7:12:54 AM

I've run this experiment a number of times(15W-50 Mobil 1 in the summer) and each time I lost 2-3 mpg. The worst case was my much-missed 1991 Accord EX coupe with a 5-speed. I went from 30-32 mpg down to 27-29 mpg and, I felt, some loss of power. Anyone else with a similar experience?
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gvan
Champion Author Chicago

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Message Posted: Jan 28, 2013 11:54:30 AM

"I use 5w-20"

Ford recommends 5W-20 because it helps with their CAFE standards but I doubt the average owner will notice a difference in mpg.
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WEPSMAN
Champion Author South Dakota

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Message Posted: Jan 28, 2013 8:07:11 AM

I have not noticed. I usually run the same oil year round. Both my cars run 5W-30 and the diesel truck runs synthetic.
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Saab93turbo
Champion Author Washington

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Message Posted: Jan 27, 2013 12:53:19 PM

Thinner oils, like 0W-20, tend to allow the car to get better gas mileage but too thin and it doesn't lubricate enough. In the old days, some sports cars used 20W-50 because the engine would get very hot.

I would recommend following the car company's recommendation but if they have several choices, then use your own judgment.

I think Mercedes Benz for some ooldercars recommends 10W-30, 10W-40
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jbhubbell
Rookie Author Alabama

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Message Posted: Jan 27, 2013 10:19:31 AM

If you use a thicker oil than the engine is designed for you run the risk of starving the heads and thats where most of the heat and moving parts are. That is dumb.
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Bridge2012
Champion Author Kansas

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Message Posted: Jan 27, 2013 8:13:44 AM

I have never changed oil for a mpg test I seam to get one kind and stay with it to the end.
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MertieMan
Champion Author Lexington

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Message Posted: Jan 27, 2013 8:03:05 AM

I am currently using synthetic oil in my Corolla S and have experienced no problems such as this, but I always change oil when it is due.
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twt
Champion Author Virginia Beach

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Message Posted: Jan 27, 2013 6:35:53 AM

I use the factory recommended viscosity, in both vehicles.
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chipote
Champion Author Washington

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Message Posted: Jan 27, 2013 4:28:58 AM

I use 5w-20
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Alexi7
All-Star Author Ohio

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Message Posted: Jan 27, 2013 3:57:41 AM

blueenvoy: Can't remember the last time I read an Owner's Manual. They're written for non-carpeople. I tried deciphering the oil change meter reset on my Pontiac G6. The tech at the dealership demonstrated an easier way and that's what I've stuck with.
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Titanic1985
Champion Author South Carolina

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Message Posted: Jan 26, 2013 9:55:05 AM

Hi Alexi7. blueenvoy & OilerFan are correct in their recommendation to follow what the Owner's Manual recommends. You included many details (especially the model year of the vehicle), but did not state the mileage on the engine. 50W oil is extremely "heavy" for today's vehicles and typically used only in those with extremely high mileage and engine wear. The tolerances of modern engines now mandate a much lighter weight of oil, usually 5W-30 or 10W-30.

You don't say, but I do hope you're not using 50W in Ohio's winter months? That is way too heavy!

Answering your question, I only use the recommended 5W-30 Dexos 1 Mobil 1 oil in my 2012 Chevrolet Sonic, so I cannot give you a valid answer.
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bluenvoy
Champion Author Nashville

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Message Posted: Jan 26, 2013 9:12:29 AM

Use what the manufacturer recommends for your engine. In the Owner's Manual.
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the1roadhog
Champion Author Atlanta

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Message Posted: Jan 26, 2013 7:39:30 AM

Interesting. I've never seen that big a difference from my standard 5/20w.
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OilerFan
Champion Author Tulsa

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Message Posted: Jan 26, 2013 7:37:56 AM

I try to stick with what the manufacturer recommends.
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